Paddlewheel fish deterrent and guide

ABSTRACT

A method of deterring fish from an underwater area includes creating a zone of turbulence along the underwater area, providing a visual deterrence to the fish within the zone, and producing a predefined level of frequency sounds along the zone of turbulence.

[0001] This application is a divisional application of U.S. patentapplication Ser. No. 09/425,866 filed on Oct. 23, 1999.

BACKGROUND OF THE INVENTION

[0002] 1. Field of Invention

[0003] This invention relates to modifying the behavior of fish.Specifically, it modifies fish behavior by using oscillating waterparticle acceleration, visual cues, and water currents.

[0004] 2. Description of Prior Art

[0005] Systems have been designed and installed to deter or guide fishfrom certain underwater areas. These areas include water intakes forhydroelectric power plants, municipal water intakes, thermal powerplants, and irrigation systems. Fish can suffer high mortalities whenthey come in contact with pumps or turbines, when they are subject totemperature variations induced by plants, or when they are pumpedthrough irrigation systems and discharged onto fields.

[0006] These systems used to deter or repel fish can be broken down intotwo categories: physical barriers and behavioral deterrents. Thesedevices and their advantages and disadvantages are described in Taft, E.P. 1986. Assessment of Downstream Migrant Fish Protection Technologiesfor Hydroelectric Application. Stone and Webster EngineeringCorporation. Electric Power Research Institute, Palo Alto, Calif.Physical barriers work by limiting the opening size of the plant intakesuch that a certain fish species or life stage of fish cannot enter.This includes barriers such as closely spaced bar racks, travelingscreens, and fixed screens. The disadvantages of these structures arethat they are difficult and expensive to construct and maintain. Theycan also limit the flow of water into the intake, thereby limiting powerproduction or quantity of water available. These structures can alsoresult in impingement of fish on the intake.

[0007] The present invention is in the behavioral deterrent category.Behavioral deterrents generate certain stimuli of which fish are knownto respond, and utilize these stimuli to deter or repel fish fromcertain areas. Known systems have employed such devices as underwaterlights, electric fields, water current/turbulence generators, visualleads such as traveling cables, and sound generators. Underwater lights(including strobes) are species-specific, and the visibility of lights,and therefore their effectiveness, is reduced in turbid water. Majorconcerns with underwater electric fields include a concern for humansafety, the variability of the field strength depends on theconductivity of water and the length of the fish, and the fact that thefield strength that is effective for some fish species may be lethal toother species.

[0008] Recently, mechanically generated water currents have been used asboth a deterrent to fish and to mimic the natural water current in theriver. The use of mechanically generated water currents and turbulenceto guide fish is summarized in Coutant, C. C. 1998. Turbulent AttractionFlows For Juvenile Salmonid Passage at Dams. Oak Ridge NationalLaboratory, Oak Ridge, Tenn. The use of water current and turbulencegenerators as a deterrent, such as air bubble curtains and water jets,is usually energy intensive and doesn't affect some species.Mechanically generated currents used to mimic natural river currentsguide fish by creating a predominant surface current (forsurface-oriented fish) across the plant intake to the area of a fishbypass. Therefore, this current has to compete with the variable rivercurrents. It is sometimes difficult to establish this continuous leadover long distances with multiple current generators without creatinggaps in the current.

[0009] Visual cues can be an effective behavioral deterrent. J. R.Brett, and D. F. Alderdice documented the use of traveling hangingcables to direct fish movement in Research on Guiding Young Salmon atTwo British Columbia Field Stations. Fisheries Research Board of Canada,Ottawa, 1958. Although this showed promise, there are operationalproblems with the system because debris in the river is likely to gettangled in the cables. Water clarity is also important with this system.

[0010] Sound is an additional means of modifying the behavior of fish.An overview of the current state of the art sound deterrent systems isprovided in Carlson, T. J. 1994. Use of Sound for Fish Protection atPower Production Facilities: A Historical Perspective of the State ofthe Art. Battelle, Pacific Northwest Laboratories. U.S. DOE BonnevillePower Administration, Portland, Oreg.

[0011] There are several disadvantages to recent sound deterrentsystems. One of the disadvantages of underwater sound deterrents is thatit is difficult to establish an uninterrupted barrier, and thus create acontinuous lead for fish to follow away from the power plant intakearea. Also, the frequency and amplitude of the sound wave must be tunedfor each individual species, and even life stage, of fish. Underwatersound systems may be categorized into either high frequency systems orlow frequency water particle motion or infrasound systems, depending onthe specific species of fish to control. Low frequency sound systemshave been proven to elicit an avoidance response in Atlantic salmonsmolts, Atlantic cod, and perch in Knudsen, F. R., P. S. Enger, and O.Sand. 1992 Awareness Reactions and Avoidance Responses To Sound inJuvenile Atlantic Salmon Smolt, Salmo salar L. Journal of Fish Biology.40: 523-534. To be effective, a sound deterrent must be able to createthe same sound repeatedly for extended periods of time withoutbreakdown. The problems the Sand system developed were that it was notmechanically reliable and that it involved the risk of electric shock.Other sound deterrents developed since then are more reliable but havedifficulty creating a continuous barrier to the fish because the soundgenerators are at point sources, such as U.S. Pat. No. 5,730,086 issuedto Truebe. Also, it has been shown in certain instances that a strongbackground noise (white noise), such as that due to turbine operation,can blanket over the effect of the sound deterrent. Without anyadditional deterrent, the fish are free to enter possibly hazardousareas.

[0012] Objects and Advantages

[0013] Accordingly, several objects and advantages of my invention are:

[0014] To provide a cost effective fish deterrent and guide.

[0015] To provide a fish deterrent and guide that incorporates multiplebehavioral deterrents to increase effectiveness.

[0016] To provide a fish deterrent and guide that is adjustable fordifferent site conditions.

[0017] To provide a fish deterrent and guide that will facilitateroutine plant operations by bypassing trash around the plant intake.

[0018] To provide a fish deterrent and guide which keeps fish in theirriver environment to reduce disease transmission and boost publicrelations.

[0019] To provide a fish deterrent and guide which improves the riverconditions for migrating fish.

[0020] To provide a continuous fish deterrent and guide.

[0021] To provide a fish deterrent and guide that will assist upstreammigrating fish in finding a fishway entrance.

[0022] To provide a fish deterrent and guide that increases fish bypasseffectiveness by reducing the velocity gradient in the fish bypassentrance area.

[0023] Further objects and advantages of the invention will becomeapparent from a consideration of the drawings and ensuing description.

DESCRIPTION OF DRAWINGS

[0024]FIG. 1 is a perspective view of the paddlewheel fish deterrent andguide with solid vanes.

[0025]FIG. 2 is a plan view of the paddlewheel fish deterrent and guidein operation at a hydroelectric plant intake.

[0026]FIG. 3 contains side views of paddlewheel fish deterrent and guidesegments illustrating different vane types. FIG. 3A shows spoked vanes,FIG. 3B shows spoked vanes in a spiral pattern, and FIG. 3C shows flatvanes in a spiral pattern.

[0027]FIG. 4 is a perspective view of the paddlewheel fish deterrent andguide in a submerged application between two piers.

[0028]FIG. 5 is a plan view of a hydroelectric site using a paddlewheelfish deterrent and guide to guide upstream migrating fish in thetailrace to a fishway entrance.

SUMMARY OF THE INVENTION

[0029] This invention is a behavioral deterrent to exclude fish frompotentially dangerous areas. It consists of an elongated paddlewheelthat is positioned across the area from which fish are to be excluded.As the paddlewheel is rotated, the effect of the vanes hitting the watersurface creates a behavioral deterrent to fish. The deterrent works inthree ways; it creates a visual clue to the fish, the sound of the vaneshitting the water surface creates a sound deterrent, and the rotation ofthe vanes through the water create current and turbulence in the water.

DETAILED DESCRIPTION OF INVENTION

[0030]FIG. 1 shows a perspective view of the present invention, apaddlewheel fish deterrent and guide. A paddlewheel 1 is comprised of acentral shaft 10, extending from which is a series of vanes 12. Eachvane 12 is constructed of a flat plate 14 extending out along the lengthof central shaft 10 in a manner similar to a conventional waterwheel.Alternatively, this plate may be curved to improve the hydrodynamics ofpaddlewheel 1. Paddlewheel 1 is of sufficient buoyancy or is suspendedfrom an adjacent structure such that the midpoint of shaft 10 is locatedat water surface 18. Paddlewheel 1 is constructed short enough tofacilitate handling. Sufficient numbers of sections of paddlewheel 1 areconnected to one another to span the hydroelectric intake area. Powertransmission between the sections of paddlewheel 1 is achieved by auniversal joint 20. Construction materials for central shaft 10 andvanes 12 may be of any material that is neutrally buoyant and hassufficient rigidity to transmit the torque provided at a power source 22to vanes 12 and water surface 18. Polyethylene pipe and sheet stock isrecommended due to its buoyancy, durability and noncorrosive properties.Flat plate 14 may be cut from plastic sheet stock and thermoplasticallywelded to central shaft 10. If negatively buoyant materials are used,floatation may be added to central shaft 10. Power source 22 used torotate shaft 10 may be located at any point in the system betweensections of paddlewheel 1. Power source 22 may be of electric,hydraulic, or pneumatic power. Power source 22 used to rotate thepaddlewheel should have a variable output to change the speed of itsrotation. This enables tuning both the frequency of the sound output andthe intensity of the turbulence so as to obtain the greatest effect forthe desired species and life stage of migrating fish.

[0031] A typical embodiment of the paddlewheel fish deterrent and guideis shown in FIG. 2. In this embodiment, the invention is used inconjunction with a hydroelectric site that includes a dam 24 and aturbine 26. Paddlewheel 1 is positioned across turbine intake 28 andleads to a fish bypass 30. Rotation of paddlewheel 1 creates a visualdeterrent as well as a turbulence and sound field 40 such that the fishare excluded from and not endangered by the turbine operation.

[0032] Operation of the Invention

[0033] The paddlewheel fish deterrent and guide commences operation whenthe shaft is rotated and the attached vanes rotate in and out of thewater. The action of the vanes striking the water surface creates a lowfrequency underwater sound. Certain species of fish, such as salmonids,have been shown to elicit an avoidance response to low frequency sounds.In addition, as the vanes rotate through the water, they create a visualdeterrent as well as movement in adjacent water particles. This movementof water particles causes a zone of turbulence in the water around thepaddlewheel. Turbulence has been shown to be an effective means ofmodifying the behavior of migrating fish.

[0034] A number of vane designs are shown in FIG. 3 to highlight theaffect of certain behavioral deterrents. Rather than flat plate 14 beingused for vanes 12, FIG. 3A shows spokes 16 extending outward fromcentral shaft 10. The use of spokes 16 increases the visual effect ofthe paddlewheel device 1. This emulates the visual deterrent and leadmade with traveling cables, without the associated maintenance problems.Spokes 16 may consist of lengths of pipe or flatbar with a smallercross-section than central shaft 10, extending through central shaft 10and welded to central shaft 10.

[0035]FIG. 3B shows spokes 16 as well, but positioned in a spiral mannerabout central shaft 10. The use of spirally positioned spokes 16 furtherimproves the visual lead because it appears that spokes 16 are movingalong central shaft 10. Also, this more closely approximates the motionof the traveling cable lead. Another advantage of this configuration isthat, as the paddlewheel is rotated, a current 38 is created parallel tothe central shaft. This resulting current not only deters fish but alsoguides them along the paddlewheel device.

[0036] In order to create a greater current 38 parallel to the centralshaft 10, FIG. 3C shows flat plate 14 arranged in a spiral patternaround central shaft 10. This arrangement retains the sound deterrentand visual deterrent effects, while producing a stronger guiding current38 as well as turbulence and sound field 40 along the paddlewheel.Alternatively, curved plates in a spiral pattern may be used in place offlat plate 14 in a spiral pattern.

[0037] Many fish species migrate in the upper portions of the watercolumn. By combining sufficient lengths of paddlewheel 1 across intake28, a barrier zone of turbulence at the water surface is created, alongwith a low frequency sound deterrent and visual deterrent, that the fishdo not wish to penetrate. Paddlewheel 1 is typically installed at anangle to the turbine intake area. Therefore, the fish swim along theouter edge of turbulence and sound field 40, following the turbine flowdownstream along angled paddlewheel 1. This leads the fish to analternate means of circumventing dam 24 and turbine 26, such as fishbypass 30.

[0038] The selection and installation process of a paddlewheel fishdeterrent at a hydroelectric site is further explained through thefollowing steps:

[0039] 1. Baseline data is first obtained from the potential site. Thisdata includes the site geometry, turbine and river flows, typical debrisin the river, the acoustic signature of any background noise (such asturbine noise), and the target species to be deterred from the turbineintake. Typical plant operations should also be noted.

[0040] 2. The location of the paddlewheel is determined by a number offactors. It has to span the turbine intake area with its terminationnear the location of the fish bypass entrance. If the background noisegenerated by the turbine is great, it may blanket over any sounddeterrent effect created by the paddlewheel. This would requireinstallation of the system further upstream away from the turbine. Theangle at which the paddlewheel sets with respect to the intake isprimarily determined by turbine and river flows. Bypass effectiveness ittypically increased if there is current along the paddlewheel leadingfish downstream once they have rejected the sound, visual cues, andturbulence generated by the system.

[0041] 3. The paddlewheel is sized based on the site data. A combinationof hydraulic calculations, lab tests, and past experience ensures thesize of the central shaft and vanes can create sufficient turbulence andoperate at the given turbine and river flows.

[0042] 4. The rotation speed of the paddlewheel is calculated based onthe target species and its known deterrence frequency. For example,Atlantic salmon smolts are known to elicit an avoidance response at 10Hz. The rotation speed is also based on the spacing between the vanesand the type of vanes utilized. To achieve an avoidance frequency forAtlantic salmon smolts with a paddlewheel that has vanes spaced at 60°,a rotation speed of 100 rpm would be required.

[0043] 5. The power source and size necessary to drive the paddlewheelis then determined based on the length, vane spacing and style, androtation speed of the paddlewheel. The power source may be floating onthe water surface or fixed to the shore.

[0044] 6. After installation of the paddlewheel, the effectiveness ofthe system should be verified with test fish. If water clarity permits,tagged fish released upstream of the intake and observed in the vicinityof the paddlewheel can provide valuable information. Adjustments inpaddlewheel angle and rotation speed based on observations will furtherimprove effectiveness.

[0045] Alternate Embodiments

[0046] An alternative embodiment of the present invention is explainedwith reference to FIG. 4. With paddlewheel device 1 positioned at watersurface 18, the present invention is primarily aimed at the deterrenceand guidance of surface-oriented fish. Alternatively, paddlewheel device1 may be constructed such that it has slight negative buoyancy. It maythen be positioned at some elevation under water surface 18 asdetermined by the elevation at which the target species of fish ismoving. Paddlewheel device 1 is positioned at this elevation by asuspension rope 32 attaching each point between the paddlewheel segmentsa float 34 at the water surface. Each end of the string of paddlewheelsis fixed to a vertical positioning rail 36. Vertical positioning rail 36is, in turn, fixed to a substantially rigid structure to preventhorizontal movement. Power source 22 may be either submerged or locatedabove water surface 18. Although this embodiment does have the advantageof deterring non surface-oriented fish, it does have some disadvantages.Since the paddlewheel is completely submerged, the vanes do not come inand out of the water, and therefore there is less of a sound deterrenteffect. This embodiment is also more difficult to maintain.

[0047]FIG. 5 is an additional embodiment showing the guidance ofupstream migrating fish 46 to a fishway entrance 44. In most situations,fishway entrance 44 is positioned to one or both sides of the turbinedischarge in the area of a tailrace 48. This is so upstream migratingfish 46 traveling upstream will cue on the edge of the turbulence andcurrent created by the turbine discharge and follow this edge to fishwayentrance 44. However, the fish become disoriented when the turbines arenot operational. In this embodiment, paddlewheel 1 is positioned intailrace 48 from shore 42 to upstream fishway entrance 44. Whenpaddlewheel 1 is rotated, it creates a defined turbulence and soundfield 40 as a lead to upstream fishway entrance 44 regardless of turbinedischarge.

[0048] The present invention provides a number of advantages to thefield of fish passage:

[0049] (a) The invention operates based on a number of behavioraldeterrent principles. Therefore, there is a backup if conditions changeand one of the deterrents is ineffective. Therefore, this increases theoverall bypass effectiveness.

[0050] (b) The turbulence and sound fields can easily be adjusted bychanging the rotation speed of the paddlewheel.

[0051] (c) The turbulence and sound fields are continuous across theturbine intake area. This provides a continuous lead, which is sometimesdifficult to obtain with point source sound generators and currentinducers.

[0052] (d) The system is relatively portable and can easily be deployedfor the fish migration period.

[0053] (e) The paddlewheel deterrent and guide can also coexist easilywith routine hydroelectric plant operations. In many instances, it isdifficult to operate fish protection devices because debris in the riverdamages them, or devices such as screens are clogged by debris. But thecreation of turbulence upstream of the paddlewheel keeps most floatingdebris away from the intake and sluices it down the fish bypass. Thepaddlewheel will simply “walk over” or “walk under” the large debristhat is not influenced by the turbulence.

[0054] (f) This system is likely to keep fish in a natural riverenvironment. This results in a reduction of disease transmission fromthose fish that are crowded during mechanical transport. A natural riverenvironment with no fish interface with mechanical structures reducesimpingement and descaling of fish.

[0055] (g) The area in which the paddlewheel is typically deployed(upstream of a dam) is in relatively slow moving, deep water in relationto the rest of the river. These river conditions can result in suboptimum conditions for the fish. This can be partially alleviated byinstallation of a paddlewheel device because it increases the dissolvedoxygen and reduces thermal stratification in the vicinity of thepaddlewheel. Also, fish have been known to move along routes of higherdissolved oxygen, which increases the guiding effectiveness of thepaddlewheel device.

[0056] (h) The invention can be used to guide upstream migrating fish tothe area of the fishway entrance regardless of turbine discharge.

[0057] Although the above description contains many specificities, theseshould not be construed as limiting the scope of the invention but asmerely providing illustrations of some of the presently preferredembodiments of this invention. Thus the scope of the invention should bedetermined by the appended claims and their legal equivalents, ratherthan by the examples given.

We claim:
 1. A method of deterring and guiding fish from an underwaterarea, said method comprising: creating a zone of turbulence along saidunderwater area; and providing a visual deterrence within said zone tosaid fish.
 2. The method of claim 1 wherein said step of creating saidzone of turbulence further comprising using a paddlewheel-shaped deviceto create said zone of turbulence.
 3. The method of claim 2 furthercomprising selecting a size and shape of said paddlewheel-shaped devicecapable of producing sufficient turbulence within said water area todeter said fish.
 4. The method of claim 2 further comprising creatingsaid zone of turbulence along a surface of said underwater area.
 5. Themethod of claim 4 further comprising determining the length of aplurality of paddles of said paddlewheel-shaped device sufficient tocreate turbulence at about a depth wherein a target species of fish areknown to migrate.
 6. The method of claim 2 further comprisingpositioning said paddlewheel-shaped device at about a depth wherein atarget species of fish are known to migrate.
 7. The method of claim 1further comprising producing a predefined level of frequency soundsalong said zone.
 8. The method of claim 7 wherein said step of producingsaid predefined level of frequency sounds further comprising selecting asize and rotation speed of a paddlewheel-shaped device to produce saidpredefined level of frequency sounds.
 9. The method of claim 1 whereinsaid step of providing a visual deterrence further comprising rotating apaddlewheel-shaped device through said water.
 10. The method of claim 9further comprising selecting a size and shape of said paddlewheel-shapeddevice to provide a visual deterrence sufficient to deter a targetspecies of fish.
 11. The method of claim 1 wherein said step of creatingsaid zone further includes creating a directional water current.
 12. Amethod of deterring and guiding fish from an underwater area, saidmethod comprising: positioning an elongated paddlewheel across a surfaceof said underwater area wherein a central elongated shaft of saidpaddlewheel is positioned at substantially the water surface of saidunderwater area; and operating said elongated paddlewheel at apredetermined rotational speed creating a zone of turbulence andproviding a visual cue for said fish within said zone.
 13. The method ofclaim 12 further comprising operating said elongated paddlewheel at arotational speed producing a predefined level of frequency sounds alongsaid zone selected for a target species of fish.
 14. The method of claim12 further comprising gathering baseline data about a specific site forsaid paddlewheel prior to installation.
 15. The method of claim 12further comprising selecting a size of said paddlewheel sufficient toprovide turbulence and a directional current within said underwater areato be effective as a fish deterrent for a target species of fish. 16.The method of claim 15 further includes selecting said size sufficientto produce a predefined level of frequency sounds sufficient to create alow-frequency sound deterring barrier for said target species of fish.17. A method of deterring and guiding fish from an underwater area, saidmethod comprising: positioning an elongated paddlewheel within saidunderwater area wherein a central elongated shaft of said paddlewheel ispositioned below the water surface of said underwater area; andoperating said elongated paddlewheel at a predetermined rotational speedcreating a zone of turbulence and providing a visual cue for said fishwithin said zone.
 18. The method of claim 16 wherein said elongatedpaddlewheel is positioned at about a depth wherein a target species offish are known to migrate.